well, i've recently been doin some research on the pros and cons of different fabrics used in training gear and i've found some interesting things about it..
i've found that the majority of performance wear is made of polyester, polyester spandex, and most rashguards (surfing ones at least) are made of nylon, nylon spandex..
here's like a guide for you newbs on fabrics and such..
It is the weave of the fabric (the size and number of holes) that determines breathability or resistance to air movement. Any woven or knit fabric will breathe - even if the weave is made of rubber strands.
is the transportation of fluids (eg. sweat in liquid form) and is driven by temperature and humidity gradient. So if the climate inside your shirt is warmer and more humid than the outside air, moisture will be driven away from your body. Wicking can also be accomplished by the construction and arrangement of yarn in a piece of clothing. If the yarn on the outside of the garment is thinner than the yarn on the inside of the garment, capillary action will pull water to the outside. The increased surface area (not hollow fibre cores) of the thin yarn gives the water more space to spread out. This type of construction can be used in either Nylon or Polyester fabrics.
is rubber that is inserted into fabric to give it stretch. Rubber is weak, however, and people can be allergic to it--Latex Allergy-- so when putting a garment with spandex in the dryer, it tends to dry out and the strands break meaning the garment loses compression power.
Polyester vs Nylon
Polyester fabrics perform better than nylon for moisture management because polyester is more hydrophobic. Nylon threads will absorb more water than Polyester, water requires more heat energy to warm than does air, so nylon will feel colder when wet, and stay wet longer, and when saturated impede breathability.
The down-side for polyester is odor retention, and durability (Nylon lasts longer).
Polyester is hydrophobic, meaning it does not absorb water. This means that when it is dyed, only the color of the dye dissolves into the fabric (not any water-base), making the dye permanent. NylonŽ possesses hydrophilic qualities (that is, it absorbs water). Its inability to repel water causes the fabric to swell and ultimately weakens the molecular structure. The dyestuffs used on nylonŽ tend to oxidize, a reaction which is catalyzed by light. The microscopic effects range from color fading to complete degradation of the polymer matrix. This is why the colors fade in nylon-lycraŽ swimsuits over time, but do not fade in polyester-lycraŽ swimsuits (Man-Made Fiber Yearbook, August 2000).
^^^also info on snagging and chlorine resistance^^^
hope this helps out some peeps in their purchasing choices